Patent GB-465645-A (GB)
Title: Improvements in the manufacture and production of coating compositions
IPC: C04B28/34
Filed: 1936-04-28
Abstract: Coating-compositions of the consistency of oil paint are made by combining aqueous solutions of one or more phosphoric acids having a specific gravity not exceeding 1,3, and free from organic binders, with one or more pigment-like oxides or hydroxides which set and harden with the phosphorie acid after application.  Specified pigment-like bodies are the oxides and hydroxides of chromium manganese, titanium, zirconium, tungsten, molybdenum, cobalt and uranium.  Fillers such as kaolin, asbestos, p  glass powder, kieselguhr and carborundum may be added.  The time of hardening may be shortened by the addition of silicates, such as those of aluminium, magnesium, calcium, zinc, zirconium, titanium and iron, with or without fluorides or silicofluorides, or hardening may be retarded by the addition of glycerine-phosphoric acid, ethylene glycol or butylene glycol. The addition of ethyl alcohol results in a very rapid hardening and drying of the coating.  When applied to metals, undesirable attack on the metallic substrata by the phosphoric acid may be counteracted by the addition of chromium compounds, such as chromic acid, chromates or bichromates.  The hardness and the adherence of the coating may be increased by the addition of phosphates, borates, tungstates and manganates, and, when a phosphate is used, its effect may be increased by the addition of a salt of a readily volatile organic acid, e.g. calcium acetate. The compositions may be prepared and used by applying two separate coatings, each lacking one or more of the necessary constituents, but which combine after application to form the complete composition, which then hardens.  If the coating is to be of a temporary nature, a loosening agent, e.g. oxalic acid, may be present, the coating thus being rendered easily removable.  When stability to high temperatures is not necessary, the coatings may be overpainted with lacquers, such as cellulose derivative lacquers, with oil paints or with chlororubber.  According to examples: (1) a coating composition, stable to red heat, consists of titanium dioxide, chromium oxide, ortho-phosphoric acid S.G.1,3, butylene glycol and water; or titanium dioxide, zirconium dioxide, chromic anhydride, orthophosphoric acid S.G.1,3 and water: (2) a coating composition, suitable for application to sheet zinc, consists of zirconium dioxide, zirconium silicate, potassium bichromate, metaphosphoric acid S.G.1,3, ortho-phosphoric acid S.G.1,3, and water; (3) a priming paint consists of zirconium dioxide, pyrolusite, chromic anhydride, glycerine-phosphoric acid, orthophosphoric acid S.G.1,3, meta-phosphoric acid S.G.1,3, and water; (4) a priming paint consists of titanium dioxide, kaolin, chromic anhydride, ortho-phosphoric acid S.G.1,3, metaphosphoric acid S.G.1,3, and water; (5) a coating composition which hardens by heating to 40 DEG  C. consists of chromium oxide, chromic anhydride, calcium silicate, magnesium silicate, kaolin, and aqueous ortho-phosphoric acid S.G.1,3; (6) a temporary and readily removable protecting coating for application to sheet iron consists of titanium dioxide, pyrolusite, chromic anhydride, oxalic acid, ortho-phosphoric acid S.G.1,3, and water. Specification 179,811, [Class 95], is referred to.  According to the Specification as open to inspection under Sect. 91, the pigment-like oxides used comprise those of the elements "from the group consisting of the first column of the fourth, sixth and seventh group and of the iron group of the periodic system." and phosphoric acids of other specific gravities may be used, but this subject-matter does not appear in the Specification as accepted.